code: def backward(self, scope: Scope, x: Array):
      for i, f in reversed(tuple(enumerate(self.flows))):
          x = scope.child(f.backward, name=str(i))(x)
      return x
  
file_path: flax/tests/core/design/core_flow_test.py
imports: from dataclasses import dataclass
  from typing import Any, Sequence
  import jax
  from absl.testing import absltest
  from jax import numpy
  from jax import random
  from jax.scipy.linalg import expm
  from flax.core import Array, Scope, apply, init, nn, unfreeze
label_desc: Use image node_id 2 for calling the StackFlow obj's underlying member method code with example usage: obj.backward(scope, x) and returns: x